# Questions tagged [current-measurement]

Measurements of the current flowing through a circuit

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### How do I tell if a shunt resistor is routed using the Kelvin method?

I am struggling to get my head around Kelvin PCB routing for shunt resistors. First how do I tell if a shunt resistor on a PCB is routed using the Kelvin method? Below are three images: THE TWO RED ...
98 views

### Simple BrainTeaser: Running an AC current between two independent amplifiers

I'm working on a project using an ultrasound method for identifying objects in water. For example, such a device could be used to locate bodies on the floor of an ocean bed after a plane crash. Our ...
681 views

### Measuring nA leakage current

I'm trying to measure some leakage currents of both a diode (expected around 5 nA) and a MOSFET (20 nA). My issue is my meter's measurement accuracy is only around 10 uA, and I need an accurate ...
1 vote
206 views

### Using two op-amps to measure the current in a predefined window

I've been trying to use an op-amp to measure the current and then use two op-amps as a comparator to detect the whether the measured current is within a window. The circuit defines the upper and lower ...
52 views

### High current/voltage power monitoring in small form factor

I am attempting to build an I/O board to integrate with software I have running on a Raspberry Pi 4. I need the board to monitor voltage and current (power would be a bonus) on 8 circuits running ...
571 views

### Neglecting certain elements in deriving the current of a series RLC circuit

The current at resonance in a series RLC circuit is described in the bottom derivation, along with it being plugged into the formula for finding the voltage across the inductor in the circuitw: I ...
44 views

What could be the reason and possible solution, for my ADC measurement on the microcontroller increasing more than the actual values, when high current is going through the circuit? I had just ...
749 views

### Hall effect current sensor ACS712 for battery application

I want to measure the current of 12V lead acid battery for charger application. So mostly, I need bidirectional current sensing. The current measurement can be done using shunt resistor or using hall ...
71 views

### Getting different answers for number of electrons in 1 amp? [duplicate]

I was looking up the number of electrons in a current with 1a and I keep on getting different answers. Some websites put the number at 6.24, some at 6.25 and others at 6.28 (all * 10^18) Is there some ...
240 views

### Dynamic control of DC-DC converter current limit

I am interested in having dynamic control of the output current limit circuit of a DC-DC converter controller (the LTC3777 buck-boost controller in my case). This IC has a built-in current limit using ...
77 views

### How can a current probe avoid saturation?

It is a buck converter, And I want to know how current probe can avoid saturation. Turns ratio is 1:1000. And DC makes transformer saturation. So... How can probe avoid saturation?
1 vote
1k views

### touch sensor for metal door handle

I was thinking if a current is applied to a metal door handled and somebody touched it that should complete the circuit to ground and be detectable but I'm not sure if this would work as the 'somebody'...
1 vote
99 views

### Microcontroller that can do 10 UART? [closed]

I am currently working on a project that would require a total of 10 UART (rx and tx pins) to run 10 PZEM-004Ts for different electrical lines. I am thinking of using an atmega 2560 because it has ...
212 views

### Measuring integrated current

I want to measure the amount of light striking a photodiode in a specific time window (about 1ms). In this window, we get $10^6-10^7$ photons, which get converted into electrons with about 80% ...
1 vote
337 views

### Asymmetrical output

I was searching for a current sense amplifier for measuring the current between a power supply and a battery i.e high side. I found the INA240A1 (evaluation module here). When I look at the ...
1 vote
4k views

### Use ACS712 current sensor in two-phase electrical system

I'm thinking about using the Allegro ACS712 current sensor for measuring house equipment current consumption (for example TV). The issue I'm facing is that my house energy supply is built around two ...
1 vote
68 views

### Whats the meaning of Im, Is and Ih

I would like to know what's the meaning for the abbreviations of Im, Is and Ih in leakage currents measurements, as it is depicted in these graphis. Could anyone help me?. The link of the source is: ...
1k views

### Why is my multimeter reading such a high/erratic current?

Newbie to electronics here. I have a simple circuit consisting of just a 9V battery and an 820 ohm resistor. I was trying to measure the current with a multimeter (by opening the circuit between the ...
1k views

### Slew rate, bandwidth and settling time

I have a system which has to be as fast as possible. The system has to sense a current across a shunt. My first idea as I have no experience on this subject would be to take a "current sense ...
69 views

### measuring microamps Arduino/esp32

I have an analogue gauge that works off a 0 to 1mA input. The gauge is for a fuel tank on a ship. Given the input current is 1 mA at the most, what can I do to make this readable on an esp32? I tried ...
168 views

### LTspice Meas Directive?

I need some help with LTspice MEAS directive. I have a simple circuit, a DC power supply, and a variable Load resistor to observe the current limiter behavior. I made the variable load resistor and ...
649 views

### Measure very small current with Arduino? [closed]

I have to make a circuit/device in which i have to measure very small current in a wire carrying ac current. In a given scenario, there will be a live wire carrying as low as 0.2A and as high as 100A. ...
1 vote
1k views

### Lightning Connector Power Output rating/ Apple Policy

I am currently in the process of developing an external antenna for smartphones, so the answer of the following question(s) pertains to the feasibility of this product. What is the line level output ...
45 views

### Scalable Voltage Display

I am trying to create my first PCB, and I am trying to measure and display scaled voltage and current output from a few different sensors on several seven segment displays. For example, one of the ...
1k views

### How to design a circuit to measure really small currents (nanoamperes for example)?

I have to design an analog circuit to measure currents in the nano ampere range as part of a course, and from what I found on Wikipedia and some documentation available online from Tektronix, it seems ...
119 views

### Test circuit for a solar panel used to power a supercapacitor

I was hoping to power a device with a supercapacitor that would provide power when there isn't light available, so essentially I just need the solar cell to charge the supercap as fast as it would ...
1 vote
64 views

### Piezoelectric Disk Charge Generation and Detection

I have a piezoelectric disk. I am trying to determine the sensitivity of this disk for the sake of making a charge model more accurate. The charge model in question: I have attached the piezoelectric ...
1 vote
276 views

### Does the burden resistance at the output of a current sensor (either Hall effect or current) represent the output impedance of the sensor?

I need to measure current though a sensor and feed it to the ADC of a micro-controller. The ADC input voltage range does not match the sensor's output voltage range. I searched and found that op-amps ...
178 views

### Current drop with capacitor

I'm new to electronics, and there's something I can't figure out. Can someone explain to me why, when I add C1, the current drops drastically in R3? I was thinking that the impedance will be the same ...
408 views

### In measuring relay contact resistance, should I use 4 wire measurement or calculate it using the voltage across the relay and current?

I'm reading mixed things online where a current from a typical ohmmeter is too low to accurately tell us the true resistance of the relay contacts. I've got a 30V 2.5A power supply, electronic load, ...
14k views

### *Very* high precision, *very* stable current source

My background: experimental physics. Not an electrical engineer, but I have some experience putting together basic electronic circuits for physics experiments. So please be kind and explain as if I'm ...
1 vote
213 views

### HLW8032 energy meter circuit showing power usage at no load

I am designing an AC energy metering circuit. The circuit has to measure voltage, current, power, power factor and energy used for two channels (from the same source). The HLW8032 transmits 24 bytes ...
2k views

### Reasons not to use these leads

I found the following note with a set of test leads we use for our Agilent 34461A[1][2]: This Test Lead Set is designed for use with the Agilent 34xxxA Multimeters, and also the U274A, U3401A, and ...
62 views

### If I connect 3 12V batteries in parallel to eachother, then connect them to the load, am I connecting to the Load in parallel or series?

I have 3 12V batteries. I have connected the 12V batteries in parallel to each other. I have 1 positive lead and 1 negative lead coming off to my motor. Am I connecting to that motor in parallel or in ...
347 views

### Measuring current with an Arduino and op-amp circuit

I want to do current measurement with a CT sensor and an Arduino with this reference. This method seems to give more accurate results output in low current (video result.) Previously I tried this ...
42k views

### Using two 14 AWG wires instead of one 12 AWG

I do understand there are many factors when choosing what AWG wire, however by the charts, tools, and info I have found, using two 14 AWG copper wires should be equal to a single 8 AWG wire. 8.025 AWG ...
1 vote
32 views

### PSC motor auxiliary winding current at full speed

In articles, e.g. here, I often find this statement: In an auxiliary winding, a counter EMF is produced as the speed of the motor increases, and this EMF will limit the current that passes through ...
44 views

### Determining load voltage and current of a pump connected to long wires

I'm trying to estimate the load voltage and current of a pump connected to a power supply with long wires. Here is a schematic: simulate this circuit – Schematic created using CircuitLab The ...
68 views

### Measure transformer real power

I’m new at making transformers myself, and the ones that I designed had the correct output voltage, and when they were connected to batteries (previously rectified), they give me a an approximate of ...
59 views

### What type of galvanometer is in this picture?

Does anyone understand the galvanometer in Faraday's experiment to the left in the picture below? How does it operate? It looks like it uses a magnet and some xy axis the needle swings over or maybe ...
62 views

### Current transducer: no voltage

I am working on a project that requires non-contact current measurement. I found the LEM LA 25-P active current transducer. I've put the connection diagram from the datasheet here. My understanding is ...
68 views

### Allegro ACS37002 - Noise Issue

I have a noise issue with the Allegro ACS37002LLAATR-015B3 (+-10A), where I see HF noise in the VIOUT signal of about +-50mV at no load attached to the sensor, which would be equivalent of around +-...
245 views

### AC current calculation from wattage and voltage

There is one simple formula to get Current drawn by the appliance i.e P = V * I I am running an appliance its wattage is 1000W as per the specs. It works on the ...
46 views

### Large current flow through SMD shunt resistor

What is the best way to large current flow through SMD resistor? As you know, latest FPGA like ULTRA series or Versal series need large Core current almost over the hundred ampere. It is not problem, ...
248 views

### Measuring soil moisture and using a vintage DC ammeter as the indicator

I have a vintage Weston Model 506 DC ammeter (it has a range of 0 to 20 amps) that has been sitting in my office and I think it would be interesting to use it as a soil moisture indicator for a (long ...
2k views

### Why do different multimeters give me very different current measurements?

I was trying to calculate R_TH using an open-circuit voltage and a short-circuit current, and I am having trouble with the current measurement. I noticed that my calculated R_TH didn’t match my ...
3k views

### Can I measure multiple wires (same current direction) with a clamp meter?

I have two wires that have current going in the same direction. Can I put them both between the clamps of a current meter and read the sum? Edit: I should mention that both wires carry DC current, and ...
1 vote
37 views

### Do we have to share the ground between a load and a sense-resistor based current meter?

I see in the datasheets of some current-meter chips, that the LOAD ground is also the same as current-meter chip (inAMP for example) ground. For example AD8293 inAMP: Or this model (INA3221) from ti: ...